A controller is typically used to control the operation of voltage level converters such as synchronous buck or buck-boost converters. Some types of conventional controllers include a digital pulse width modulator (DPWM) for generating control signals used to operate the voltage level converter circuit, e.g., by driving the gates of transistors devices included in the voltage converter. The DPWM is a part of a closed-loop error control function for regulating the voltage output by the voltage level converter circuit. However, the feedback signals processed by the controller must be converted from the analog to digital domain prior to processing by the PID control and the DPWM. The analog-to-digital conversion process increases bias supply power consumption and induces delay. The overall phase margin of the controller is reduced when delay is added to the signal processing path. To compensate for reduced phase margin, the controller typically over-samples at higher switching frequencies. However, over-sampling increases complexity and power requirements.
In addition, a DPWM inherently has relatively low resolution compared to an analog equivalent PWM circuit. As such, the digital signals processed and output by the DPWM have restrictions on their precision, reducing the ease of designing with the DPWM as a control element in a voltage level converter circuit. The DPWM can also introduce limit cycle oscillations during operation of the voltage level converter if the digital controller is not designed properly. DPWMs also tend to be larger than their analog counterpart PWMs, consuming more silicon area and thus increasing overall system cost. Other types of digital voltage level converter control circuits tend to be implemented by converting the functionality of an equivalent analog circuit to the digital domain block-by-block. Converting an analog design to the digital domain block-by-block is inflexible and lengthens the circuit design process and may create incompatibility issues for next-generation designs.